一株抗Cd~（2＋）菌株的筛选及其吸附性能

Cd2＋为一种毒性金属元素,为了实际解决污水中低浓度重金属污染,实现污水达标排放,通过12C6＋重离子束辐照诱变技术筛选到一株耐受Cd2＋的菌株C2,研究其对Cd2＋的抗性和低浓度Cd2＋的吸附性能表明,Cd2＋浓度≤100 mg/L时,C2菌株可以生长繁殖,但随Cd2＋浓度升高受到抑制;SEM分析表明,受到Cd2＋胁迫时,C2产生大量胞外产物与Cd2＋形成络合物;吸附过程中菌粉表面空隙得到填充,形成凸起;红外光谱分析表明,吸附过程中的主要作用基团为醇羟基O—H键、氨基和酰胺基团;C2菌粉和固定化菌球都对Cd2＋有较好的吸附能力,菌粉吸附效果比固定化菌球稍好;菌粉和固定化吸附剂的最佳吸附初始pH值为5~6.0,最佳投加量分别为1.0 g/L和10 g/L（实际含菌量为1.0 g/L）;Cd2＋浓度在2~20mg/L时,在最佳吸附条件下,菌粉和固定化吸附剂对Cd2＋的吸附率均在90%左右;2种吸附剂吸附过程与Langmuir等温模型和拟二级动力学模型拟合最佳;热力学研究表明吸附反应均能自发进行。以上研究结果表明,C2菌粉和固定化吸附剂均可用于污水中低浓度Cd2＋的去除。

Screening of a Cd~（2＋） -resistant bacterium and its biosorption

In order to remove the low concentration Cd2＋ from effluent,a bacterial strain C2 isolated from sludge was mutated by heavy ion beams,which was tolerated with Cd2＋ . According to the resistance against Cd2＋ and the absorbability of low concentration of Cd2＋ ,the results as following,C2 was able to grow on Cd2＋ concentration ≤100 mg/L,while the growth was inhibited with the Cd2＋ concentration increased. Scanning electron microscopy（ SEM） of C2 indicated that the extracellular products were produced by the microorganism,which could combine with Cd2＋ formed complex,and the surface interspace of bacteria powder was filled to formed humps after Cd2＋ was absorbed. The fourier transform infrared spectroscopy（ FTIR） data showed that the functional group of hydroxyl and amino and amide played a principal role for the adsorption. Bacteria powder and immobilized bacteria ball of C2 could be used as biosorbent for the removal of Cd2＋ from aqueous solution,the adsorption capacity of bacteria powder was better than the immobilized bacteria ball. Adsorption capacity of bacteria powder and immobilized bacteria ball was influenced by pH value,mass concentration,temperature and time observably. The optimal pH value and mass concentration of bacteria powder was 5 ~ 6 and 1. 0 g/L,and for the immobilized bacteria ball,which the actual content of C2（ dry weight） was 1. 0 g/L,the optimal pH was 5 ~ 6 and 10. 0 g/L. Under the optimal conditions,the removal rate of Cd2＋ reached approximately 90% by the bacteria powder and immobilized bacteria ball,and the concentration of Cd2＋ increased from 2 to 20 mg/L. The experimental data were also fitted to isothermal and kinetics model and thermodynamic equation. The parameters indicated that bacteria powder and immobilized bacteria ball were fitted well with Langmuir isotherm model,and the actual absorption process was identical relatively with pseudo-second-order Lagergren mode,and the biosorption process was happened spontaneously according to thermodynamic parameters. The above results showed that both the bacteria powder and immobilized bacteria ball could be used to remove Cd2＋ of sewage effectively.